Japanese Laid-Open Patent Publication No. 9-219957 discloses an actuator device equipped with a drive motor, a reduction mechanism including gears, and an output shaft. Rotation of the drive motor is transmitted to the output shaft via the reduction mechanism, thereby driving a driven device coupled to the output shaft. The actuator device also includes a power supply terminal connected to the drive motor, a sensor for detecting the rotational angle position of the output shaft, and connector pins connected to an external connector. Drive current is supplied to the drive motor from the outside and rotational angle signals obtained by the sensor are sent to the outside through the external connector.
The connector pins are held between an upper case and a lower case, which form a connector housing. The power supply terminal is located on a first conductive plate and the connector pins are located on a second conductive plate. After the second conductive plate is crimped to the first conductive plate, spot welding is performed so that the first and second conductive plates are coupled to each other. A patterned substrate forming part of the sensor is adhered to one of gears forming the reduction mechanism. A brush connected to the first conductive plate slides against the patterned substrate.
The actuator device has the following drawbacks. That is, since the connector pins are held between the upper case and the lower case, which form the connector housing, it takes time to accurately arrange the connector pins at a predetermined position in the connector housing. Also, since the first conductive plate, which has the power supply terminal, needs to be coupled to the second conductive plate, which has the connector pins, maintenance and assembly of the two conductive plates are complicated and troublesome. Furthermore, it is difficult to check the contact state between the patterned substrate adhered to the gear and the brush. As a result, it takes a lot of trouble to assemble the actuator device of the above publication.
Like the above publication, Japanese Laid-Open Patent Publication No. 9-308188 discloses an actuator device equipped with a drive motor, a reduction mechanism including gears, and an output shaft. According to the actuator device of the publication No. 9-308188, one of the gears (except a worm attached to a rotary shaft of the drive motor) forming the reduction mechanism is pressed in the axial direction by a spring washer. The pressure on the gear applies force on the rotary shaft of the drive motor along a direction that intersects the axial direction of the rotary shaft. As a result, backlash of the rotary shaft is suppressed.
In the above publication, a special spring washer is provided to press one of the gears in the axial direction. Therefore, manufacture and an assembling process of the spring washer are required, which increases the manufacturing cost of the actuator device.